This invention relates to a vertical engine for a walk behind lawn mower and more particularly to an improved arrangement for lubricating an engine of the type having its cylinder disposed in a horizontally extending position.
Normally, internally combustion engines are operated in an orientation so that the cylinders are disposed generally vertically or at an angle to the vertical. In many applications, however, it is desirable, if not necessary, to operate the engine with the cylinders horizontally disposed. For example, in many types of engine powered implements, such as rotary lawn mowers, it is desirable to operate the engine so that the output shaft rotates about a vertically extending axis. This permits the engine output shaft to be directly coupled to the driven element, such as the rotary mower blade in a mower of this type. The positioning of the engine with its cylinders extending horizontally presents certain problems, however. For example, if the engine is lubricated by a splash type system, it may be difficult to insure that the components are adequately lubricated. In addition, this type of engine application normally employs air cooled engines. As a result, it is further desirable to ensure that adequate quantities of lubricant flow across certain components of the engine to provide cooling in addition to lubrication.
For example, if the engine is provided with a valve operating mechanism that includes overhead type valves, it is essential to ensure good lubrication of the valve train. However, the horizontal disposition of the push rods and rocker arms and valve stems makes it difficult to insure good lubrication, particularly when a splash type lubrication system is employed. In addition, it is desirable to insure that the exhaust valves are adequately cooled with such an arrangement.
It is, therefore, a principal object of this invention to provide an improved lubricating system for an engine having its valves disposed in a horizontally extending position.
It is a further object of this invention to provide an improved system for lubricating and cooling the horizontally disposed exhaust valve of an internal combustion engine.
It is still a further object of this invention to provide an improved system for lubricating and cooling the valves in an engine of the splash lubricated type wherein the valves are horizontally disposed.
In connection with certain components of the valve train of an internal combustion engine, as is well known, there are provided clearances for normal operation and to allow for differences in thermal expansion. That is, it is the normal practice to provide a clearance in the operating mechanism for the valve train. Because of this clearance, noise is generated and it is desirable to provide an arrangement for minimizing the transmission of these noises externally of the engine. One way that this can be done is to immerse the components having the clearance in lubricant. However, this is difficult to do with horizontally disposed engines.
It is, therefore, a still further object of this invention to provide an improved arrangement for immersing components of the valve train of an engine in lubricant when the valve train components are horizontally disposed.
It is another object of this invention to provide an arrangement for entrapping lubricant in the area of the valve operating mechanism of a horizontally disposed engine.